<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>

    <script>
        window.onload = function () {
            class Person {
                constructor(name, age) {
                    this.name = name;
                    this.age = age;

                }

                lop = 2;

                unname() {
                    alert(this.name);
                }
            }

            class Student extends Person {
                constructor(name, age, school) {
                    super(name, age);
                    this.school = school;
                }

                show_school() {
                    alert(this.school);
                }

                unname() {
                    alert('bbq');
                }

            }


            let p = new Person('111', 11);
            p.unname();
            alert(p.lop);

            let s = new Student('111', 11, 200);
            s.unname();
        }

    </script>
</head>
<body>

</body>
</html>